Key lock for calculating machines



June 24, 1930. A. A. HOR N AL 1,767,673 KEY LOOK FOR CALCULATING MACHINES Filed March 5, 192a 4Sheets-Sheet 1 lllll All HHIIHHI vnvv HHHI INVENTOR 66% 0 Mm alwfifl a m r ATTORN EYS June 24, 1930. A HQRTQN ET AL 1,767,673 I KEY LOCK FOR CALCULATING MACHINES Filed March 5. 1928 4 Sheets-Sheet 2 INVENTOR L BY flu Vfimwy a ATTQRNEYS June 24, 1930. f A. A. HORTON E AL KEY LOCK FOR CALCULATING MACHINES Filed March 5. 19 28 7 4 Sheets-Sheet '4 5 INVENTORS y I ywlnl? ATTORNEYS Patented June 24, 1930 UNITED STATES PATENT OFFICE ALLEN A. HORTON, 0E PLYMOUTH, AND CHARLES MARTI, 'OE LIVONIA TOWNSHIP, WAYNE COUNTY, MICHIGAN, ASSIGNORS TO BURROUGHS ADDING MACHINE COM- PANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN KEY LOCK FOR CALCULATING MACHINES Application filed March 5,

.before being again depressed. If a key is not fully depressed, the mechanism for its bank may not be operated to the full extent required to register the proper number, and

likewise, if a key is not allowed to fully restore before it is again depressed, the mechanism corresponding to that bank may not get a full stroke of movement because it is not allowed to return to normal in order to start at the beginning of the stroke. Constructions have been provided which have for their object insuring that the keys shall be fully depressed, but it is not so important that the keys be fully depressed as it is that the counter be operated properly to correctly register the value of the keys that are depressed. The actuating mechanism operated by the keys has a certain momentum which may carry it forward to its fully operated position even though the key that .has operated it may be stopped sli htly short of a fully depressed position. If a locking mechanism is provided which depends upon the key itself, the locking mechanism operates even though the actuating mechanism, through its momentum, has really moved the counter properly so that there is no need for a locking action. The present invention is directed, among other things, to a 'solution'of 3 partially depressed and enough to'oper'ate the key locking mecha- 'msm;

this problem.

It is, accordingly, an object of the inven tion to rovide a lockingmechanism for locking the keys of a key driven calculator when the to the proper extent ,for the keys that are manipulated.

Another feature of the invention concerns the locking of all the keys in all the banks when a misoperation has occurred and it is in the accompanying mg the principal trated tion on the bf Eig. 2;

actuating mechanismis not moved 7 parts when the 8 1928. Serial No. 259,168.

an object of the invention to provide a mechanism that will accomplish this result.

St ll another object of the invention is to provide a means for automatically covering the numeral dials when a misoperation occurs so that the operator cannot read the figures on the counter or register.

It is therefore a more particular object of the invention to provide an improved mechanism for locking the keysof a calculator against depression and for obscuring the numeral dial when a key is only partially depressed.

Another object is to provide an improved mechanism for locking the keyboard of a calculator and obscuring the numeral dial when a. key is 'depressedbefore being allowed to fully restore to its normal position from a prior depressionl Other objects and advantages of the invention will appear from the specification and drawings.

,An embodiment of the invention is shown I drawings, in which: Figure 1 1s a sectional side elevation showparts of a calculating machine with which the invention is illus- Fig. 2 is a partial sectional side elevation showing the invention applied to the machine, all parts being in normal position;

Fig. 3 is a partial section and front elevaconstruction board;

Fig. 4 is a of one of the keys of the keypartial section on the line H Fig. 5 is a sectional side elevation corres onding to Fig. 2 showing the position of t e parts when the 8 keyhas been only then released far Fig. 6 is a partial sectional side elevation, similar to Fig. 5 showing the position of the key has been fully de- P s Fig. 7 is a view similar the position of the parts when an attempt has been'made to depress a key a second time line 3-301 Fig. 2 showing the I to Fig. 2 showing I before odor nrior :lueuressio b Fig. 8 isa artial sectional side elevation with some or the carts omitted ilh nting how the keys of the keyboard are locked against depression;

Fig. 9 is a side elevation of the right-hand. side of the machine with the-casing removed show a the clearing handle and the mechanism 1-1 restoring th locking devices to normal position; v

Fig. 10 is a detailed side elevation of the indexing hers used on the calculator;

Fig. 11 is a plan -view oi a portion of the front of the machine showing the numeral dial exposed with certain figures appearing thereon:

Fig. 12 is a View corresponding to Fig. 11 showing how the numerals are covered when the machine has misoperated;

Fig. 13 is partial side elevation of a modified torm oi? the locking mechanism.

The invention is shown applied to a key driven calculator ot the Bur-mu; type, the general features of one bank of which are illustrated in Fig. 1, it being understdod that the machine i. made up of a plurality 01' similar hanks. Each bank has a plurality of amount beginning with the 1 key at the front and ending with the 9 key at the back. Each key has a stem 10 such as illustrated in detail in- Fig. 3 and each is urged upwardly by a spring 11. \Vhen one of the keys is depressed its side projection strikes the bar 13 and depresses it which oily restore from. a

resu ts in rocking the bracket 1st (Fig. 1)

about its pivot against the tension of the spring 15. This thrusts the indexing bar 16 forward and the latter is connected to a toothed sector 17 which operates a counterpinion through suitable mechanism, such as described tor example, in Horton Patents ll 1,016,501 and No. 1,156,600. Each of the keys has a lateral lug 18 (Fig. which when the key is depressed, projects into the path of a tooth 19 on the indexing bar 16. There is a tooth 19 for each key and these are located so that they engage only their respective key stems and so that. the movement of the indexing bar is such as to move the toothed sector 17 a proper number of steps corresponding to the valucof the key depressed. The 9 key does not limit the indexing bar by means of its lug 18. Instead, the bar is given a full stroke of movement when the 9 key is depressed, but it is limited to a nine stop movement- ,by the engagement of the pivot stud 20 with the end of the arcuate slot 21 in the partition plate 22 illustrated in Fig. 1.

1t will be obvious that, if a key is only pai tially depressed. the bar 13 will not-be moved downward the full distance to rock the bracket 11- to thrust the indexing bar 16 forward the proper distance to cause a registration of an amount corrcspor i,

key de n'e sed. Likewise. it clout t at, if, at i; a key has been 1' it is allowed to return to normalv before being in depressed, the indexing her will no? "u returned to its rearward p: "ion airfh t 'nsequently, the sector 17 will not be given a lull stroke, but will.bc started tot-ward :gain before it has returned to H5 normal position. The actual registration of the number in the counter occurs upon the rear- Slidably mounted on each indexing bar lli is an auxiliary indexing bar Ilt 'lhcrr is one of these auxiliary bars for each of th main indexing liars and nch auxiliary bar has projections 31 correspomliug to the projections 19 of the main bar. The auxiliary bar is mounted on the main bar to lidc on the headed studs 3"). illustrated in ch Fig. 10, and a spring 233 is connected between the two bars in such a manner as to ur th auxiliary bar forward to position its pro-- jcctions 31 slightly ahead of the projections 19 on the main bar. A stud, Jilprojc laterally trom the main bar 1 into the slot 35 in the auxiliary bar for a purpose which will presently appear.

Pivotcd on the rear stud 32 on the main indexing bar 16 is a pawl 86 illustrated in Fig. 2 which is urged coouter-clockwise b a spring 37 one end of which connected to the pawl and the other cnd of which rests on the stud 34. In the normal position of? the parts, movementof the pawl countcr-clocliwise is limited. by the engagement oi the tail 38 of the pawl with a stud 39 on the partition Counter-clockwise movement of the pawl is also prevented under these couditions by the engagement of the pawl with a square studell on the auxiliary indexing bar 80 as shown in Fig. 2. The pawl is provided with a shoulder 42 which may move in front of the square stud 41 under certain conditions hereinafter described. The pawl is provided at its rear end with a lateral lug 43 which cooperates with the teeth 44 of a locking dog 45 pivoted by a pin and slot connection on the shaft 46 and provided with a tail piece 47 positioned in a slot in the shaft 48. The locking dog 45 is urged forwardly. or to the right in Fig. 2, by a spring 19, one end of which is connected to the dog and the other end to a second locking dog 50 which is also mounted by a pin and slot connection on the shaft 46. The second dog is provided with teeth 51 facing in the opposite direction of the teeth 44 0f the dog 45. The spring 49 serves to urge the dog 50 rearward as well as to urge the dog 45 forward. lVhen one of the keys is depressed, as for example, the 8 key, both the main and the auxiliary indexing bars move forward. The pawl 36 moves forward with the main bar and the tail of the pawl moves away from the stud 39, but the pawl is prevented from moving counter-cloclnviseby the square stud 41 on the auxiliary indexing bar. The lat-- eral lug 43 of the pawl 36 rides over the teeth 44 and the parts are free to'move forward. If the key is fully depressed to the position illustrated in Fig. 6, the parts assume the positions there shown. As the indexing bars reach the limit of their forward movement, the tooth 31 on the auxiliary bar strikes the stem of the depressed key slightly before the tooth 19 of the main bar, which results in stopping the auxiliary bar while 42 beyond the the main bar moves forward relative to it. The pawl 36, which is mounted on the stud 32 onthe m'ainbar, moves forward with the main bar sufficiently to move its shoulder stud 41 whereupon the spring 37 snaps the pawl counter-clockwise to the Fig. 6 position and lowers the lateral lug 43 on the rear end of the pawl out of the path of the teeth 44 on the locking dog 45.

- the engagement of a stud'52 (Fig. 4) on the a frame plate 53 in- \Vhen the key is released after being fully depressed, it moves upward andthe indexing bars move rearward carrying with them the pawl 36, whose lateral lug 43 then rides over the teeth 51 on the dog 50. v

If the key is allowed to fully rise to its normal position, the pawl rides over all the teeth 51 and, as the indexing bars reach their normal position, the tail 38 of the pawl 36 engages the stud 39 and the pawl is moved clockwise to its F 2 position where it is again in position for another operation, the auxiliary bar 3Q.being drawn slightly forward by the spring 33 to position the stud 41 over the'shoulder 42 of the pawl 36.

In case the 9 key is operated as above described, the auxiliary bar 30 is limited by bar with the edge of steadof by the 9 key stem.

In the event a key, such as the 8 key, is released after having been pa-rtiall depressed, the locking means becomes e ective in the following manner. 7 At the time the key is released after being only partially depressed, the indexing bars have not moved forward to their full extent and the lateral lug on the pawl 36 has not passed over all of the teeth 44 on the locking dog 45. The main barhas not moved forward relative to the auxiliary bar to cause the shoulder 42 of pawl 36 to clear the stud 41 and the pawl has not been moved counter-clockwise by the spring 37.

, the indexing the spring 49,

being a dog 73 for each bank down to the Accordingly, the lateral lug 43 has not been ,moved out of the path of the teeth 44 as oc-' curs in a full depression. As soon as the key is released it moves upwardly under the influence of its restoring springll, and the indexing bars tend to return rearward and to carry the pawl 36 with them. However, the lateral lug 43 on the pawl 36 immedis at-ely-engages one of the teeth 44 on the locking dog'and the rearward movement of i bars is stopped. \Vhen the pawl 36 engages the locking dog 45 it moves the latter rear-wardly against the tension of such movement being limited bytheshaft4.

-Pivoted at to the jacent the locking dogs 45 and 50 is a three armed lever 61, the lower arm of which has:

a lateral lug 62 for engagement by a downwardly extending projection 63 on the dog 50 and the upper arm of which has a lateral lug 64 for engagement by a projection 65 on the locking dog 45. The third arm 66 of its lever extends forward and upwardly to a point where it engages an arm 67 connected to a cross bail 68 pivoted on studs 69 on the machine side frames. Resting against the bail 68, as illustrated in Fig. 2, is an arm 70 of a second bail 71 pivoted at 72' to the machine side frames and extending across the machine in the rear of a series of pivoted dogs 73 illustratedin Fig. 8, there of keys, but only one being shown. The dog 73 has a projection 74 and a cut out portion 7 5 on its rear side and a. projecting nose 7.61011 its front side, the latter co-operating with one of a series of pivoted dogs 77illustrated in Fig. 8. There is a dog 77 between each of the adjacent key stems, said dogs forming interlockin pression of more than one key at the same time. The dogs have projections 78 extending under'lugs 79 in the key stems and the width of the dogs is such that there is just enough lost motion in the whole series to admit one of the key stems. After one of the key stems has moved down none of the other [keys can be depressed because there is no space between the dogs 77 for the admission of a second key stem. The dog-73 is normally ficient distance to admit one key stem between the 77 and the dog 73, owing to the fact that the bail 71 is of thedog but the movement of the dog is limited to an'extent sufficient to permit only one key to be depressed at a time by the engagement of the surface 75 of dog'73 with the bail 71. Vhen the bail 71 is moved position illustrated in Fig. 8, the dog 73cannot move rearwardly and none of the keys can be depressed since there is partition plate 40 ad 5 in front of the cut out portion devices for preventing the dc free to move rearwardly a sufv stems.

partially do erciiofore c illust ated in Fl the locks moved rearwai y explained and its projection G5 conthe lug (A on the three-armed lever the latter counter-clockwise, thereby causing the upper arm (36 to rock the bail to free the arm'TO to permit it "0 drop down to the position of Fig. This 0 es the bail Tl to the position illustrated ip. S to lock all of the keys against de- This includes the row of keys in key was only partially depressed when said key was released, it

e L one.

wnicli it b cause,

'"ioved upward to normal thereby allowing dogs '7? and 73 for that row LU move to normal after which the bail 71 blocks movement of the dogs for said row the same as it does for the other rows.

It will be observed that the locking action dey epds upon the position of the indexing If these bars move forward by meoars.

mentuin to their proper position. the keys are not locked even though one of them may not have been quite fully depressed.

Dial obscuring inc ms e downward movement of the arm '70 bail Tl also moves a shutter .across the opening through which the numeral dials are normally visible, such result being accomplished. through connections illustrate jl in lie arm has a forward extension carrying a stud 81 positioned in a slot in the end of a lever 82 pivoted at to the machine side frame and having a forward extension 84- provided with a bifurcated end extending over a lateral lug 85 on the arm 86 which is pivoted on the dial shat 8T. lhe arm 86 is connect-ed to the shutter 88 which is movable from the posiion illustrated in Fig. 9 to the position shown in Fi 12 where the shutter is directly across the openings 89 in the casing 90. The pivot d arm 82 is urged clockwise by spring 91 and the shutter is urged connter-clockwise by a counter-weight 92, said spring and counter-weight assisting in moving the arm 70 downward after it has been released by the upward inoveincntof the bail G3. The shutter prevents the operator from reading any of the figures when the machine has been misoperated and this is particularly advantageous where misoperation occurs in the last one of 'a series of operations. Under such conditions the operator would not need to use keys again and even though they were locked he would have no warning were it not for the fact that the shutter immediately obscures the figures and prevents him from reading the result.

* as predepressed key is lateral lug Locking actioii--partial metal-(Mimi of a. key

so that the tailSS of the pawl 36 has not yet contacted the stud 39. Accordingly,

when the key is again depressed with the resulting forward movement of the main in dexing bar which carries with it the pawl 36, the lateral lug 48 on latch 36 engages one of the teeth 51 on the locking dog 50 and further forward movement of the indexing bar is prevented which thereby prevents further depression of the other keys in the same bank is also prevented owing to the fact that the stem of the semibetwcen the interlocking dogs 73.

During the operations above described the wrong amountmay have beci'i'recorded and it is desirable'to have further operation of the machine prevented when the particular key in question is released. This is automatically accomplished upon release of the key that has been depressed before having been allowed to fully restore from a prior depression. \Vhen the pawl 36 engages a tooth of the dog 50 during the ope 'ation above described it moves the dog forwardly and the projection 63 on the dog engages the (32 of the member (51 to rock the latter counterclockwise. This counterclockwise movement of the member 61 results in moving the bail 68 clockwise to release the arm 70 to permit the bail 71 to move down to lock the keys against depression and to permit the lever 82 to be locked clockwise to move the shutter 88 across the openings 89. The bail 71 does not move down to the full limit of its movement as long as the key is held depressed because of the projection on the left hand dog 73 of Fig. 8 but the. movement is enough to cause the shutter to be moved to dial obscuring position. As soon as the key is released. said dog 73 moves forward thereby freeing the bail 71. which lhereupon moves down to lock all the keys.

Assume, for example. that the S key. Depression of I the opening through which the numeral wheels are visible.

When pressure on the partially restored key is released it automatically rises to fully restored position, thereby permitting the indexing bars to move rearward which causes the tail 38 of the pawl 36 to strike the stud 39 and move the pawl to its normal position so that these parts are conditioned for-another operation, butthe machine remains in locked condition and can be. released only by operating the following mechanism.

Restoflhg. mechanism After the keys have been locked and the shutter moved across the openings 89, the

machine can be released only by moving the fixed to it which is urged clockwise by a spring 103, the clockwise movement being limited by a projection 104 on the frame that is engaged by a stud 105 on the arm. The stud 105 is adapted to engage a cam pro'eetion-106 on the tail of a lever 107 pivote at 108. The rearwardlyextending end of the lever 107 bears upon a lateral projection of-anarm 109fixed to the shaft 48 which-extends across the machine and which has a slot. in it for reception of the tail 47 of the locking dog as illustrated in Fig. 2, it being understood that the shaft 48 has a slot for 'each key bank. The spring .91 which urges the lever82 clockwise is also connected to the lever 107 to urge it counterclockwise into engagement with the stud 105.

At the beginning of a forward stroke of the handle 101, the stud 105, actin on the projection 106, cams the lever 107 c ockwise which gives-the shaft 48 a slight clockwise movement as viewed in Fi 9 or a; counterclockwise movement as viewed in Fig. 5. The turning movement of the shaft 48 cams the tail 47 of dog 45'-downward and rocks the dog clockwise to lift its teeth out of the path of the lateral lug 43 on the pawl 36. \Vhen the parts are in the position illustrated in Fig. 5, as a result of the locking of them by release of a key after a partial depression, the above 'action releases the indexing bars for movement back to normal, which movement occurs and carries the pawl 36 rearwardly where it is'moved to normal position by the engagement of its tail 38 with the stud'39. The indexing bars and associated parts are thus restored to position for another operation. Such restoration is not necessary when the locking is due to depression of a-key after a partial restoration as illustrated in Fig. 7, because, as soon as pressure on the key is released, the parts above mentioned automatically move to normal without requiring that the o erating handle be manipulated. The i nipulation, of the clearing handleboth when l the locking occurs by partial depression and 1\{vhen it occurs by partial restoration of a ey. v

The arm 102 has a second stud 110 operating in a short slot 111 in 'a link 112 and in a longer slot 113 in a parallel link 114. The forward end of link 112'ha's a slot 115 operating over a stud 116 on a pivoted arm 117 which restores the pinion of the counter to 0 position by mechanism which is wellknown in the Burroughs calculator and which need not'be described here. The link 114 is pivoted on the stud 116 without any Sliding connection and the two links are interconnected by a spring 118. The spring 118 urges thelink 112 rearward against the stud 119 projecting from link 114. The two links are urged rearwardly by a spring 120 connected to an arnr 121. bearing against a stud 122 on link 112, the rearward move- 'ment of the links-being limited by the stud 123 on link 114 which strikes a frame web 124 on the machine. i As the clearinghandle 101 is pulledforward it carries the arm 102 Wltll it. and moves the arm 117 counter-clockwise to'restore the counter pinions to 0. The short sl0t111 in link 112 is provided in order that the link-112 will not be picked up until after the stud has operated lever 107 to rock the'shaft 48' to release the indexing bars so that they canmove to normal prior to the restoration of the counterpinions. ,In the event the countermechanism should become locked in some manner, the forward movement of handle 101 will simply move the link 112 forward to stretch the spring 118, such movement of the link being permitted by the lon slots 113 and 115. This action protects ;t e' counter against such damage as would occur under the above cir cumstances by the use of a positive operating connectionand, at the-same time, gives an'efiective operating connection under normal condition; y

If there has been a 'misoperatio'n of the -machine, the lever 82 will have been moved clockwise and its forward end will be close to. or in contact with; the stud 119 on the link 114. As the link 114 is moved forward by the handle the stud 119. cams the forward end 84 of the-lever 82 downward and rocks the lever counterclockwise. This moves the arm 70 clockwise to move the bail 71 out of locking position, and all the keys are thus unlocked. The arm 70 is moved clockwise past the bail 68 which thereupon drops back toposition so that, when the lever 82 is released, the arm 70 will drop back against thebail 68 which will hold the parts in the normal position illustrated in Fig. 2. The counterclockwise movement of the lever 82 acting through the spring 91 also tends to more the lever 10? back to normal to pernnt 70 contacts the bail 68. As the handle moves back to its home position the stud 105 moves under the shoulder 106 to the position of Fig. 9.

Modified locking mechanism In the eventit should be desirable to lock a partially restored key against a second depression Without locking all the keys, such a result can be accomplished by a slight modification in the construction of the locking dog such as shown in Fig. 13.

In this construction the dog 50 is pivoted on shaft l6 without any sliding movement and it is provided with ten or more teeth 51 corresponding to the nine keys of its key bank. \Vhen a key is depressed a. second time before being allowed to fully restore, it is instantly locked against depression by the locking dog 50 in the manner heretofore described. However, the second depression of the key does not move the dog 50 forward and hence the three-armed lever 61 is not rocked to release the locking mechanism for the keys. \Vhen pressure on the depressed key is released, it restores to normal and operations may be continued.

It is to be understood that the construclion shown is for purposes of illustration only and that variations may be made in it without departing from the spirit and scope of the invention as defined by the appended claims.

lVe claim:

1. The combination in a key driven calcu later of depressible keys for operating the machine, a counter, means operated by par-" t'al depression and release of any one of the keys for locking all of the keys against depression, and a single means for releasing said locking means and clearing the counter.

2. The combination in a key driven calculating machineof depressible keys for operating the machine. means urging said keys to a normal position,--and means operated by depression of any one of the keys before it has been allowed to return to normal from a prior depression for locking all the keys against depression. i

3. The combination in a calculating ma chine of depressible keys, means urging said keys to =1 normal position, and means operated both by partial depression and release of any one of the keys and by depression of any one of the keys before it has been allowed to restore to normal from a prior depression for locking all the keys against depression.

4. The combination in a calculating machine of banks of depressible to definite positions, interlocking means between the keys of each bank to prevent more than one key from being depressed at a time, locking means cooperating with the interlocking means of all the banks of keys for Tendering said interlocking means effective to prevent depression of any of the keys, and means operated by partial depression and release of any one of the keys for causing said locking means to become effective to lock all the keys against depression.

5. The combination in a calculating machine of banks of depressible keys, means urging said keys to a normal position, interlocking means between the keys of each bank to prevent more than one key of a bank from being depressed at a time, locking means cooperating with the inter-locking means of all the banks of keys, and means operated by depression of any one of the keys before it has been allowed to return to normal from a prior depression for causing said locking means to become ellective to lock all the keys against depression.

6. A key-driven calculating machine hav ing banks of keys dcpressible to definite positions to operate said machine, an indexing bar foreach bank, locking means for locking all the keys against depression, a pawl for each indexing bar for operating said locking means upon. partial depression and release of any key of its bank, and means operated by full depression of a key of any bank for rendering the pawl for said bank ineffective to operate said locking means by .release of a key of said bank but rendering it effective to operate said locking means by depression of any one of the keys of its bank before said key has been allowed to return to normal from a prior depression.

7. The combination in a calculating machine of banks of deprcssible keys, means urging said keys to a normal position, means for locking-all the keys against depression, an indexing bar for each bank of keys, a. pawl foreach bar for operating the locking means when a. key is depressed before it has been allowed to return to normal position from a prior depression, and means operating on said pawl as a depressed key reaches normal position for disabling the pawl from operating the locking means upon depression of the key. I

8. The combinationin a calculating machine of banks of depressible keys, an indexing bar for each bank, a locking means for locking all the keys against depression, a pawl associated with the indexing bar of each bank having connections foropcrating said locking means upon partial depression and release of any key of, its bank, means operating upon full depression of a key in v a bank or rendering said pawl for said bank to its first operating position.

' 9. The combination in,a calculating machine of depressible keys, means urging said keys to a normal undepressed position, a.

' counter having visible meansfo} indicating the amount of the items thecbunter, and means automatically rendering-paid indicating means invisiblewhen one ofthe keys "}s depressed before havingbeen allowedto illy restore to its normal prior depression.

- 10. The combinatlon in a calculatingmw chine ofdepressible keys, means urging said position from a keys toward a normal position, a counter having visible means indicating the amount of the items in the counter, and means antomatically rendering said indicating means invisible when one of the keys is only partially depressed and when one of the keys is depressed before having been allowed to fully restore to its normal position from a prior depression.

11. The combination in a key drivencalculating machine of depressible keys, means urging said keystoward a normal position, a counter having visible dials indicating the amount of the items "in the counter and a shutter mechanism operated to obscure vision of said dials by depression of any one of said keys before it has been allowed to return, to normal position from a prior depression.

12. The combination in a calculating machine of keys depressible to definite positions, a counter having visible means'indieating the amount of the items in the counter, and means operating automatically when any one of the keys is released after being only partially depressed to lock all the keys against depression and to render said indicating means invisible.

13. The combination in a calculating machine of depressible keys, means urging said keys to a normal position, a counter having visible means for indicating the amount of the items in the counter, and means operated automatically when anyone of the keys is released after having been depressed before it was allowed to restore to normal from a prior depression to lock all the keys against depression and to render said indicating means invisible. v

14. The combination in a calculating machine of keys depressible to definite positions, means urglng sald keys to-a normal position, a counter having vislble means for counter, and means operated automatically by partial depression and release of an one has been depressed before it was allowed to restore to normal from a prior depression for locking allthe keys against depression and for rendering said indicating means in- .visible.

15. The combination in a 'key driven calculating machine of depressible keys for operating-said machine, acounter having visible dialsoperatively associated therewith for indicating the amount of theitems in the counter, and means operated by partial depression an release of-any one of the keys for looking all of the keys against depression and for moving a shutter to obscure vision of the indicating dials.

16. The combination in a key driven calculating machine of depressible keys for operating said machine, means urging said keys to a normal position, a counter having visible dials operatively associated therewith for indicating the amount of the items in the counter, and means operated by depression of any one of the keys before it has been allowed to restore to normal from a prior depression for looking all of the keys against depression and for moving a shutter to obscure vision of the indicating dials. 17. The combination in a calculating machine of banks of depressible keys, means urging said keys to a normal position, a counter having visible dials for indicating the amount of the items in the counter, means operated both by partial depression and release of any one ofthe keys and by depression of any one of the keys before it has been allowed to restore to normal position from a prior depression, said last named means acting, when so operated, to lock all the keys against depression and to move a shutter to render said dials invisible, and means operated by a single manipulative member for clearing the counter, releasing the locking means, and moving" the shutter to normal position.

18. The combination in a key driven calculator of depressiblekeys, actuating inechanism operated by depression of the keys for actuating a counter, and means controlled by said actuating mechanism for looking all thekeys against depression when one of the keys is released after being only partially depressed. i

19. The combination in a key driven calculator of depressible keys, actuating mechanism operated differentially by said keys to actuate a counter, and means operated by said actuating means for locking all the keys against depression when said actuating indicating the amount of the items in the of the keys and by release of any key a ter it means is not moved to its full extent of movement for the key that is depressed.

20. The combination in a key driven calculator of depressible keys, means urging said keys toward a, normal undepressed position, actuating mechanism operated by depression of the keys for actuating a counter. and means controlled by said actuating mechanism acting to lock all of said keys against depression when one of the keys is depressed before it has been allowed to fully return to normal from a prior depression.

21. The combination in a key driven calculator of depressible keys. a .,hanism operated by depres for actuating a counter, n r actuating mechanism toward a normal nonoperated position, and means operated by said actuating mechanism to lock all the keys against depression when said actuating mechanism isurged toward its operated position beforehaving been allowed to return to normal "from a prior operation.

22. A calculating machine having banks of depressible keys, :1 main indexing barter each bank, an auxiliary indexing'bar for each bank movable with the main bar and movable relative thereto said auxiliary bar being indexed slightly ahead of said main bar, a locking means for looking all of said keys against depression, a pawl for each bank having connections for operating said ocking means, each pawl being controlled by its main and auxiliary indexing bars and being operable u-pon partial depression and release of a key in its bank to operate said locking means, and means operable by relative movement of the auxiliary and main indexing bars for any bank when said bars are indexed to render the pawl for said bank effective to operate said locking means on depression of zr'key prior to full restoration of said key from aaprior depression.

A calculating machine having banks of depressible keys, a main indexing bar for each bank, an auxiliary indexing bar for each bank movable with the main bar and movable relative thereto, a locking whensaid main indexing bar is moved to normal.

2a. A key-driven calculator having banks of depressible keys, an indexing bar for each bank operated by depression of the keys of its respective bank, locking means for locking all the keys against depression, and operating connections controlled by said indexin bars for operating said locking means w ien one of the keys is released after being only partially depressed, said operating connections being conditioned for operation of the locking means until the indexing bar for the bank in which a key is depressed reaches its indexing position, but being disabled when said indexing bar reaches itsdridexing position irrespective of the extent of depression of the key that has been actuated to move said bar.

A key-driven calculator having banks of depressible keys, an indexing bar for each bank, a locking means for locking all of the keys against depression, operating "connections for each bank controlled b its indexing bar for operating the loc 'ing means, said operating connections being oftective to operate said locking means when a key in a bank is depressed before being allowed to return to normal from a prior depression, and means for disabling said operating connections as to said locking action on return of the indexing bar for said bank .to normal irrespective of the exact return movement of the key that has been operated to operate the indexing bar.

In witness whereof, we have subscribed our names. 7

ALLEN A. HORTON. CHARLES MARTI.

means for locking all of said keys against depression, a. pawl carried by each main bar having connections for operating said lockirgmeans, a device on each auxiliary bar ;or normally maintaining the pawl of its in position to operate said locking means upon a partial movement and release the main indexing bar of said bank, said device acting upon relative movement of the main. and auxiliary bars when they are indexecto release said pawl to permit it to move to a position to operate said locking means on an attempt to index said main indexing bar before it has returned to normal irom prior movement, and means for returning said pawl to its normal position 

